A thermal printer used for a POS (point-of-sale) terminal controls the transport speed of a recording medium such as a receipt paper according to the print rate of print data printed on the recording medium. Also, the thermal printer includes a plurality of heat generating elements arrayed in a direction orthogonal to the transport direction, and drives the heat generating elements, based on a pulse signal with a predetermined pulse width corresponding to the transport speed.
The thermal printer needs to properly control the heat generating elements until a target transport speed is reached. If control information for the heat generating elements is provided for each available transport speed in combination with a target transport speed, the number of pieces of control information of the heat generating elements increases as the number of available transport speeds increases. For example, if there are three available transport speeds, six pieces of control information are needed.
In view of the foregoing, a transport speed control device that can reduce the number of pieces of control information of the heat generating elements until a target transport speed is reached, while maintaining the number of available transport speeds, is desirable.